The present invention relates to a three-side trimmer for cutting the top edge, the bottom edge and the fore edge of a booklet bundle comprising a multiple of stacked booklets so as to trim them.
In bookbinding, after aligning the back of a pile a predetermined number of papers, adhesive is applied on its back surface and a cover is attached thereon so that a booklet is formed. The top edge, bottom edge and the fore edge of the booklet are cut respectively by a top edge cutting knife, bottom edge cutting knife and fore edge cutting knife in a three-side trimmer so as to be trimmed. After this treatment, the booklet will be conveyed to the next treating process.
Recently, in order to improve the efficiency of bookbinding, it becomes common that a booklet bundle is formed. And the booklet bundle is positioned in a predetermined position in a three-side trimmer, then the top edge, bottom edge and the fore edge of the booklet bundle are cut simultaneously.
FIG. 9 is a schematic view of a three-side trimmer in the prior art. Referring to FIG. 9, a booklet bundle 2 is conveyed by a conveying belt 3 into the three-side trimmer 1 in the direction indicated by the arrow A in the figure. Reference numerals 4a, 4b denote a convey claw pressing the bottom edge of the booklet bundle 2, and 5a, 5b guides for guiding the fore edge and the back edge of the booklet bundle 2, respectively. When the booklet bundle 2 enters into the alignment portion C and the top edge of the booklet bundle 2 contacts with a top edge guides 7a and 7b, the booklet bundle 2 stops. Then the fore edges of each of the booklets in the booklet bundle 2 are aligned so as to form a plane, by means of an alignment plate 11.
Reference numeral 6 denotes a back edge guide, 8 a servomotor, 9 a ball screw, arid 10 a chuck attached to the ball screw 9. When the servomotor 8 is driven, the ball screw 9 is driven to rotate through a connecting journal mechanism so that the chuck 10 moves in the direction indicated by the arrow B in the figure.
After aligning the fore edge, top edge and the bottom edge of each of the booklets in the booklet bundle 2, the booklet bundle 2 is pinched by the chuck 10. Then, the servomotor 8 is driven so as to drive the ball screw 9 to rotate. Thus, according the movement of the chuck 10, the booklet bundle 2 is conveyed along the direction of the arrow B shown in the figure, which is perpendicular to the conveying direction A of the convey belt 3, and finally arrives to the cutting portion D.
In the cutting portion D, the booklet bundle 2 is pressed from the upper side thereof by a pressing plate (not shown), and the booklet bundle 2 is fixed to a stationary position. Then, the fore edge, top edge and the bottom edge of each of the booklets in the booklet bundle are cut, respectively by means of a fore edge cutting knife 12, top edge cutting knife 13 and bottom edge cutting knife 14.
FIG. 10 is a side view of the alignment portion C and the cutting portion D, seen from the direction of arrow E, shown in the figure. The chuck 10 comprises a fixed block 10b for supporting the bottom surface of the booklet bundle 2 and a moving block 10a, which can move up and down with respect to the fixed block 10b, as shown in FIG. 10. The moving block 10a is driven by a proper driving mechanism, for example, an air cylinder or a cam mechanism. The moving block 10a has a waiting position, the height of which is higher than the height of the booklet bundle, and a working position for pinching the booklet bundle in cooperation with the fixed block 10b. Thus, the pinching of the booklet bundle 2 by the chuck 10 is carried out by the moving down of the moving block 10a in the direction indicated by the arrow P from the waiting position so as to pinch the booklet bundle 2 in cooperation with the fixed block 10b therebetween
In this case, the height of the booklet bundle 2 depends upon the height of each of the booklets and the number thereof in the booklet bundle 2. Therefore, the height of the waiting position of the moving block 10a can be so designed that the height corresponds to the maximum value of possible height of the booklet bundle 2 so as to prepare to respond easily to any change of the height of the booklet bundle 2.
However, when the height of the waiting position of the moving block 10a is so designed that it corresponds to the maximum value of the possible height of the booklet bundle 2, it would take rather long time to lower the moving block 10a for pinching the booklet bundle 2 in cooperation with the fixed block 10b, if the height of the booklet bundle is rather low compared to the expected maximum height of the booklet bundle 2. As a result, it takes a longer time to convey the booklet bundle 2 from the alignment portion C to the cutting portion D. Additionally, it takes a longer time to convey the next booklet bundle into the alignment portion C. Consequently, there arises a problem that a longer time is required to cut a booklet bundle.
Reduction of the time required for the preparation of the booklet bundle cutting may be realized also by driving the moving block 10a by means of, for example, air cylinder or hydraulic cylinder so that the block moves in high speed for pinching the booklet bundle. However, in this case, the moving block 10a collides with the booklet bundle at a high velocity, and there arises a problem that the booklet can be injured. Considering these problems, in three-side trimmers in the prior art, the moving block 10a is designed to move in a short stroke region. And in the initial state, the waiting position of the moving block 10a is set at an arbitrary height. The level of the height of the waiting position is adjusted in response to the height of the respective booklet bundle so that a high speed treatment can be realized.
The cutting portion D comprises a pressing plate 18 and a driving motor 19. A power transmission means 15, for example, timing belt, is connected to the driving shaft of the driving motor 19 so as to transmit the power to the pressing plate 18 through a nut 16 and a screw 17. The pressing plate 18 can be positioned at a waiting position, which is positioned at a point higher than the height of the booklet bundle 2, or at a working position for pressing the booklet bundle 2 from the upper side thereof. A signal corresponding to the height of the booklet bundle 2 to be cut is inputted to a controller of the driving motor 19. The controller outputs a control signal in response to the height to the driving motor 14. In this way, the pressing plate 18 moves down from the waiting position in the direction indicated by the arrow Q to the working position to press the booklet bundle 2.
The pressing plate 18 is designed similarly to the moving block 10a. Namely, in order to avoid the injuring of the booklets and simultaneously to realize a high-speed treatment, the pressing plate 18 moves in a short stroke region. And the height of the waiting position can be adjusted in response to the height of the booklet bundle so as to press the booklet bundle properly.
Accordingly, in the tree-knife trimmer in the prior art, data for determining the height level of the waiting block must be inputted for each batch of booklets, considering the height of each of the booklets. The data is inputted to the control portion of the driving means for the moving block of the chuck, which is disposed in the alignment portion. Thus, there arises problems that the handling of the three-side trimmer is not simple, and long time is necessary for the trimming treatment.
Moreover, such three-side trimmer cuts a plurality of booklets simultaneously, therefore, the number of the booklets have to be counted at sight for each trimming treatment. The counted number shall be summed to get the total number of the trimmed booklets. The summing of the number of the trimmed booklets is bothersome. And there is a problem that mistakes can take place in the summing.